The name Ismelda has its origins in Old Spanish and Old Galician. It is a feminine form derived from the Germanic name Ismilda or Ismildis, which in turn comes from the elements "is" (iron or sharp) and "mildi" (gentle or soft). The contrasting elements suggest a strong yet gentle nature.

In the early Middle Ages, the name Ismilda or Ismildis was fairly common among the Germanic tribes that settled in the Iberian Peninsula after the fall of the Roman Empire. As the name evolved into the Spanish and Galician languages, the form Ismelda became prevalent.

One of the earliest recorded instances of the name Ismelda can be found in the 12th-century Codex Calixtinus, a medieval manuscript associated with the Santiago de Compostela cathedral in Galicia. It mentions an Ismelda who was a member of the local nobility in the region.

Throughout the Middle Ages and Renaissance, the name Ismelda was used primarily in Spain and Portugal, though it remained fairly rare. A notable bearer was Ismelda de Sousa (1370-1438), a Portuguese noblewoman and lady-in-waiting to Queen Philippa of Lancaster.

In the 16th century, the Spanish conquistador Pedro de Valdivia named the city of La Serena in Chile after his wife, Ismelda de Aguilar. This helped to spread the name to the New World and Latin American territories.

Another historical figure was Ismelda de Mascarenhas (1530-1605), a Portuguese courtier and companion to King Sebastian I. She accompanied him on his ill-fated military campaign in Morocco, where he was killed in the Battle of Alcácer Quibir.

In the 19th century, Ismelda Martínez (1835-1897) was a Cuban poet and writer who became known for her romantic and patriotic verses during the struggle for Cuban independence.

While not as common as some other Spanish names, Ismelda has endured as a unique and historic name with deep roots in the Iberian Peninsula and its cultural legacy.